222 FLORA INDICA.
mountains round the Pangong lake, and Captain Richard
Strachey and Mr. Winterbottom a very valuable one in Ghige
in the autumn of 1849. Mr. Lance has also sent us, through
Mr. Edgeworth, a collection from Piti, Ladak, and Dras, which
contains many interesting species.
Our attempts to divide Western Tibet into provinces have
been attended with unusual difficulty, owing to the undefined
limits" of those already established, and to the fact that the
natives of that country have no system of nomenclature for
large areas, mountain chains, or rivers, available for our pur-
pose. Considering how scanty the flora of Western Tibet is.,
not amounting perhaps to more than 500 species, and how
widely the majority of these are spread, any division into
provinces might perhaps have been dispensed with,so far
as the purposes of geographical distribution are concerned;
but the flora of the country is far too imperfectly known in
detail to warrant the assumption that particular habitats arc
wholly useless; and we should farther be depriving future
local botanists of the benefit of our local knowledge.
In the following attempt we have been guided wholly by
the river systems, which enable u& to divide the country
into three parallel lines of provinces, that occupy (within
rough limits)1. The north slope of the Himalaya; 2. The
beds of the Indus and Satlej; 3. The south.slope of the
Kouenlun; they are as follows :
1. Guge, the Tibetan course of the Satlej.
2. Piti and Parang, the basins of the rivers of those names,
tributaries of the Satlej.
. 3. Zanskar, the basin 6f the Zanskar river.
4. Dras, the basin of the Dras river,
5/Nari, the upper course of the Indus.
6. Ladak, the middle Tibetan course of the Indus.
7. Balti, the lower Tibetan course of the Indus and of the
8. Nubra, the upper basins of the Nubra and 8havuk.rivers,
tributaries of the Indus.